Erosion performance of detonation gun deposited WC–12Co, Stellite 6 and Stellite 21 coatings on SAE213-T12 steel

ABSTRACT Thermal spray coatings are used to improve the erosion resistance of boilers and turbine components for power plants and other industries. In this work, detonation gun spraying method is used to deposit WC-12Co, Stellite 6 and Stellite 21 coatings on SAE213-T12 boiler steel. The coatings were characterized using microhardness tester, scanning electron microscope (SEM), optical microscope and X-ray diffractometer (XRD). The solid particle erosion behaviours of the coatings were evaluated at 30° and 90° impact angles using an air jet erosion test rig. The erosion rates of Stellite 6 and Stellite 21 coatings are found approximately 60% and 50% respectively higher than WC–Co coating, which might be attributed to the respective hardness of the coatings. Cobalt content in the coatings played an important role on the erosion behaviour of the coatings. The erosion mechanisms of the coatings involved micro-ploughing, micro-cutting along with some micro-cracking and hard phase pull-outs.